Physicochemical forces which sequester cell solutes from soluble form to organized structures are investigated from the standpoint of molecular conformations of components and of their interacting species. Earlier results showed that ordered, negative charges (e.g., in glycosaminoglycans) have profound and specific ordering effects on amine cations. The current project studies the role of polyanions in inducing conformational constraints in otherwise non-ordered cationic polypeptides. A variety of purified polysaccharides (PS) from plant, bacterial, and mammalian sources, investigated for their conformation-promoting effects on poly-L-lysine at neutral pH, showed little specificity; all PS with sufficient anionic density promoted a high degree of alpha-helical conformation. Investigation of specificity dependent upon peptide structure revealed that interactions of heparin (and other polyanions) with L-lysine:1-tyrosine copolymer promote the Beta-protein structure, while those with L-lysine:L-phenylalanine copolymer induce alpha-helical order. The finding that the nature of conformational changes in protein models due to interaction with heparin varies, depending upon constellations of amino acids and their proclivity for alpha-helix or Beta-structures, is significant in the molecular basis of heparin and other multianion action in granule formation and enzyme activation. BIBLIOGRAPHIC REFERENCES: Stone, Audrey, L.: Optical conformation of heparin complexes with cationic dyes, amines, and protein models. Fed. Proc. 36, 101-106, 1977. Stone, Audrey L. and Epstein, Paul: The aggregation of basic polypeptide residues bound to heparin. Biochim. Biophys. Acta 497, 298-306, 1977.